Hard Disk questions

[Kevin O'Gorman]

In article <701 at argon.UUCP> ebh at argon.UUCP (Ed Horch) writes:
>In article <19995 at cup.portal.com> thad at cup.portal.com (Thad P Floryan) writes:
>>MB, formatted (UNIXPC, 16 sec/trk)	40.3			67.1
>>(ignoring the spare sec per track)
>
>What does the Unix PC do with that extra sector?  Is that how it
>remaps bad blocks?

Yes, the 17th sector is used for spares.

Note that a sector is half a logical block, so this arrangement makes some
sense: in the normal course of things, almost all blocks are read as two
consecutive sectors on the same track.

Also note, that when you specify bad blocks by logical block number, the
system pretty much has to assign alternates for both of the pysical sectors.